This research is concerned with the following topics as applied to electrocardiography; 1. The effect of inhomogeneities on the electrocardiogram. This is studied by means of an eccentric spherical heart in a spherical torso which appears both simple yet capable of accounting for the major effects both of structure (geometry) and electrical conductivity of torso inhomogeneities. 2. Activation models are being formulated and examined on both a cellular and macroscopic basis -- including the interrelationship of each. Such models are tested against electrophysiological experiments which utilize intracellular, multiple intramural, and epicardial electrodes. Furthermore, interpretations of the latter measurements will be examined in the light of the source/volume-conductor conditions.